Dissolution of hexamine in non-aqueous solvent

ABSTRACT

The present disclosure generally relates to scavenging hydrogen sulfide. The disclosure pertains to non-aqueous and non-volatile compositions that include a monolignol alcohol and hydrogen sulfide scavenging compound. The hydrogen sulfide scavenging compound may be hexamine in some aspects. The compositions may also include a C2-8 polyol. The compositions disclosed are stable and can be used, for example, in removing hydrogen sulfide from hot asphalt.

BACKGROUND 1. Field of the Invention

The present disclosure generally relates to scavenging hydrogen sulfide.More particularly, the disclosure pertains to the use of non-aqueoushexamine compositions to scavenge hydrogen sulfide present in asphalt.

2. Description of the Related Art

Petroleum asphalt is produced as a residue of a thermal separationrefinery process. The thermal separation process causes thermal crackingto occur which frequently causes hydrogen sulfide to be present in theasphalt stream. In fact, thermal cracking continues in the asphalt evenafter the asphalt has left the vacuum distillation section of theoperation, particularly at high temperature. In order to permit the safeloading, handling, and storage of the asphalt, it is necessary to reducethe hydrogen sulfide to safe levels in the asphalt. This has been donein the past by weathering of the hot asphalt for sufficient time for thehydrogen sulfide to be reduced to safe levels. This not only takes aconsiderable amount of time (several days), but it releases hydrogensulfide to the vapor space in the storage, which could create hazardousconditions. Moreover, recent emphasis on environmental regulations inEurope stresses the limits on the hydrogen sulfide content of vent gas.

BRIEF SUMMARY

In some embodiments, a composition is provided that includes amonolignol alcohol and a compound of formula (I) or formula (II)

where R₁ may be a substituted or unsubstituted C₁₋₃₂ alkyl, asubstituted or unsubstituted C₂₋₃₂ alkenyl, or a substituted orunsubstituted C₂₋₃₂ alkynyl. The substituted C₁₋₃₂ alkyl, thesubstituted C₂₋₃₂ alkenyl, and the substituted C₂₋₃₂ alkynyl may besubstituted with hydroxyl or C₁₋₅ alkyl.

In some embodiments, the monolignol alcohol is selected from the groupconsisting of p-coumaryl alcohol, coniferyl alcohol, sinapyl alcohol,cinnamyl alcohol, and any combination thereof. The monolignol alcoholmay be cinnamyl alcohol. The monolignol alcohol may be coniferylalcohol. The compound may be hexamine.

In some embodiments, the composition comprises a C₂₋₈ polyol. The C₂₋₈polyol may be glycerin.

In some embodiments, the composition comprises the compound of formula(I), cinnamyl alcohol, and glycerin.

In some embodiments, the composition comprises about 2 to about 20weight percent of the compound of formula (I) or formula (II). Thecomposition may comprise about 10 to about 98 weight percent of themonolignol alcohol. The composition may comprise about 2 to about 80weight percent of the C₂₋₈ polyol.

In some embodiments, a weight ratio of the monolignol alcohol to theC₂₋₈ polyol is about 10:1 to about 20:1. In some embodiments, a weightratio of the compound of formula (I) or formula (II) to monolignolalcohol is about 1:15 to about 1:1.

In some embodiments, the composition comprises an amount of water thatis less than about 1% by weight. In some embodiments, the compositionexcludes water.

The composition may comprise a pH greater than about 7.

In some embodiments, a method is provided for scavenging hydrogensulfide in an industrial process. The method may include adding aneffective amount of a composition to a medium in the industrial process.The composition may include a monolignol alcohol and a compound offormula (I) or formula (II)

where R₁ is a substituted or unsubstituted C₁₋₃₂ alkyl, a substituted orunsubstituted C₂₋₃₂ alkenyl, or a substituted or unsubstituted C₂₋₃₂alkynyl, wherein the substituted C₁₋₃₂ alkyl, the substituted C₂₋₃₂alkenyl, and the substituted C₂₋₃₂ alkynyl are substituted with hydroxylor C₁₋₅ alkyl.

In some embodiments, the composition of the method further comprises aC₂₋₈ polyol and the monolignol alcohol is cinnamyl alcohol.

In some embodiments, the effective amount is in a range from about0.00001 ppm to about 100,000 ppm.

In some embodiments, the medium is selected from the group consisting ofcrude oil, diesel fuel, asphalt and any combination thereof.

The foregoing has outlined rather broadly the features and technicaladvantages of the present disclosure in order that the detaileddescription that follows may be better understood. Additional featuresand advantages of the disclosure will be described hereinafter that formthe subject of the claims of this application. It should be appreciatedby those skilled in the art that the conception and the specificembodiments disclosed may be readily utilized as a basis for modifyingor designing other embodiments for carrying out the same purposes of thepresent disclosure. It should also be realized by those skilled in theart that such equivalent embodiments do not depart from the spirit andscope of the disclosure as set forth in the appended claims.

DETAILED DESCRIPTION

Various embodiments are described below. The relationship andfunctioning of the various elements of the embodiments may better beunderstood by reference to the following detailed description. However,embodiments are not limited to those illustrated below. In certaininstances details may have been omitted that are not necessary for anunderstanding of embodiments disclosed herein.

Environmental standards and safety standards require the removal ofhydrogen sulfide from oil, asphalt, or other materials. Variousstrategies and chemicals are used to remove hydrogen sulfide.

Hexamine can be used as a hydrogen sulfide scavenger. Hydrogen sulfidescavenger refers to compounds that may eliminate hydrogen sulfide orreduce its concentration in a medium such as oil, asphalt, or diesel.Hexamine decomposes in the presence of acid to ammonia and formaldehyde.

Formaldehyde or ammonia can then react with hydrogen sulfide convertingthe volatile and toxic gas into a nonvolatile material. Despite theusefulness of hexamine, it has limited solubility in common solvents.Some solvents that can effectively dissolve hexamine are volatile andincompatible with compositions that need to be added to hot asphalt.Additionally, hexamine is available in at least two different forms.Hexamine can be in a hexahydrate form that melts below room temperatureat 13° C., which is generally described as an “aqueous solution” ofhexamine. Hexamine can be in a pure solid form with a melting point ofabout 280° C.

Hexamine has limited solubility in most common organic solvents at 20°C.: 13.4 g in chloroform, 7.25 g in methanol, 2.89 g in ethanol, 0.65 gin acetone, 0.23 g in benzene, 0.14 g in xylene, 0.06 g in ether, andnear zero in petroleum ether. Chloroform is not suitable due totoxicity, and ethanol and acetone are too volatile for use in use in hotasphalt, which can be up to 300-400° F.

The present disclosure seeks to solve the problems associated with thesolubility of hexamine. The compositions may be non-aqueous andnon-volatile, which is ideal for applications involving hot materialsuch as asphalt. The compositions may be halogen-free, which isdesirable for improved worker safety.

In some embodiments, a composition is disclosed for scavenging hydrogensulfide. The composition may include a hydrogen sulfide scavenger. Thehydrogen sulfide scavenger may be a compound of formula (I) or formula(II) as shown below,

where R₁ may be a substituted or unsubstituted C₁₋₃₂ alkyl, asubstituted or unsubstituted C₂₋₃₂ alkenyl, or a substituted orunsubstituted C₂₋₃₂ alkynyl. The substituted C₁₋₃₂ alkyl, substitutedC₂₋₃₂ alkenyl, and substituted C₂₋₃₂ alkynyl may be substituted with ahydroxyl group or a C₁₋₅ alkyl.

In some embodiments, R₁ may be a substituted or unsubstituted C₁₋₈alkyl, a substituted or unsubstituted C₂₋₈ alkenyl, or a substituted orunsubstituted C₂₋₈ alkynyl. The substituted C₁₋₈ alkyl, substituted C₂₋₈alkenyl, and substituted C₂₋₈ alkynyl may be substituted with a hydroxylgroup or a C₁₋₅ alkyl.

The term “alkyl,” as used herein, refers to a linear or branchedhydrocarbon radical, preferably having 1 to 32 carbon atoms (i.e., 1, 2,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,23, 24, 25, 26, 27, 28, 39, 30, 31, or 32 carbons). Examples ofunsubstituted alkyl groups include methyl, ethyl, n-propyl, i-propyl,n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, i-pentyl, s-pentyl,t-pentyl, and the like.

The term “alkenyl,” as used herein, refers to a straight or branchedhydrocarbon radical, preferably having 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 39,30, 31, or 32 carbons, and having one or more carbon-carbon doublebonds. Alkenyl groups include, but are not limited to, ethenyl,1-propenyl, 2-propenyl (allyl), iso-propenyl, 2-methyl-1-propenyl,1-butenyl, and 2-butenyl.

The term “alkynyl,” as used herein, refers to a straight or branchedhydrocarbon radical, preferably having 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 39,30, 31, or 32 carbons, and having one or more carbon-carbon triplebonds. Alkynyl groups include, but are not limited to, ethynyl,propynyl, and butynyl.

In some embodiments, the compound of formula (I) may be hexamine, whichis also known as hexamethylenetetramine, methenamine, urotropine, or1,3,5,7-tetraazatricyclo[3.3.1.1^(3,7)]decane. Hexamine is readilyavailable from common chemical suppliers.

The composition may also include a monolignol alcohol. Monolignolalcohols may be isolated from various species of plants and trees. Themonolignol alcohol may be p-coumaryl alcohol, coniferyl alcohol, sinapylalcohol, or cinnamyl alcohol.

In certain embodiments, the composition may have about 2 to about 20weight percent of the compound of formula (I) or formula (II). Theamount of the compound of formula (I) or formula (II) in the compositionmay range from about 5 to about 20 weight percent, about 5 to about 15weight percent, or about 7 to about 12 weight percent. In someembodiments, the amount of the compound of formula (I) or formula (II)may be about 7 weight percent, 8 weight percent, about 9 weight percent,about 10 weight percent, about 11 weight percent, about 12 weightpercent, about 13 weight percent, about 14 weight percent, or about 15weight percent.

Monolignol alcohols originates from certain plants, such as grass, andcan be purchased from chemical suppliers at varying degrees of purity.The monolignol alcohol in the composition may include a mixture of oneor more of p-coumaryl alcohol, coniferyl alcohol, sinapyl alcohol, orcinnamyl alcohol, including any other monolignol alcohols.

In other embodiments, the monolignol alcohol may be p-coumaryl alcohol.

In some embodiments, the monolignol alcohol may be coniferyl alcohol.

In some embodiments, the monolignol alcohol may be sinapyl alcohol.

In some embodiments, the monolignol alcohol may be cinnamyl alcohol.

In certain embodiments, the monolignol alcohol may be a mixture of oneor more of p-coumaryl alcohol, coniferyl alcohol, sinapyl alcohol, orcinnamyl alcohol.

In some embodiments, the composition may consist of the compound offormula (I) or formula (II) and a monolignol alcohol. The compositionmay consist of the compound of formula (I) and cinnamyl alcohol. Thecomposition may consist of hexamine and cinnamyl alcohol.

In some embodiments, the composition may have about 10 to about 98weight percent of the monolignol alcohol. In other embodiments, themonolignol alcohol present in the composition may range from about 20 toabout 98 weight percent, about 30 to about 98 weight percent, about 40to about 98 weight percent, about 50 to about 98 weight percent, about60 to about 98 weight percent, about 70 to about 98 weight percent, andabout 80 to about 98 weight percent.

In other embodiments, the composition may include a C₂₋₈ polyol. Apolyol may be defined as an alcohol having multiple hydroxyl groups. Insome embodiments, the composition may include a C₃₋₈ polyol, a C₄₋₈polyol, or a C₅₋₈ polyol. The composition may include a C₃ polyol.

In some embodiments, the C₂₋₈ polyol may be glycerin. Glycerin ishydroscopic and may contain water. Water content in commerciallyavailable glycerin can be as low as about 1% by weight or less. In someembodiments, the composition may include an amount of water that is lessthan about 1% by weight. The glycerin may be prepared such that all thewater may be removed by using molecular sieves, for example. In certainembodiments, the composition may exclude water.

In some embodiments, the composition may have about 2 to about 80 weightpercent of the C₂₋₈ polyol. The amount of C₂₋₈ polyol in the compositionmay range from about 2 to about 70 weight percent, about 2 to about 60weight percent, about 2 to about 50 weight percent, about 2 to about 40weight percent, about 2 to about 30 weight percent, or about 2 to about25 weight percent.

In some embodiments, the composition may include the compound of formula(I) or formula (II), cinnamyl alcohol, and a C₂₋₈ polyol. Thecomposition may include the compound of formula (I) or formula (II),cinnamyl alcohol, and glycerin. In other embodiments, the compositionmay consist of the compound of formula (I) or formula (II), cinnamylalcohol, and a C₂₋₈ polyol. The composition may consist of hexamine,cinnamyl alcohol, and glycerin.

In some embodiments, the weight ratio of the monolignol alcohol to theC₂₋₈ polyol may be about 10:1 to about 20:1, about 1:2 to about 20:1,about 1:1 to about 20:1, or about 1:10 to about 10:1. In certainembodiments, the weight ratio of the monolignol alcohol to the C₂₋₈polyol may be about 15:1.

In some embodiments, the weight ratio of the compound of formula (I) orformula (II) to monolignol alcohol may range from about 1:20 to about1:1. In other embodiments the weight ratio may range from about 1:15 toabout 1:1, about 1:15 to about 1:2, or about 1:15 to about 1:5. In someembodiments, the weight ratio of the compound of formula (I) or formula(II) to monolignol alcohol may be about 1:8.

In some embodiments, the composition may have a pH greater than about 7.The composition may have a pH of about 7 to about 9. Generally, it maybe desirable to maintain the pH at neutral or alkaline conditions beforeadding to the asphalt to avoid acid hydrolysis of hexamine.

In some embodiments, a method is provided for scavenging hydrogensulfide in an industrial process. The method may include adding aneffective amount of a composition to a medium in the industrial process.The composition may include a monolignol alcohol and a compound offormula (I) or formula (II)

where R₁ is a substituted or unsubstituted C₁₋₃₂ alkyl, a substituted orunsubstituted C₂₋₃₂ alkenyl, or a substituted or unsubstituted C₂₋₃₂alkynyl, wherein the substituted C₁₋₃₂ alkyl, the substituted C₂₋₃₂alkenyl, and the substituted C₂₋₃₂ alkynyl are substituted with hydroxylor C₁₋₅ alkyl

In some embodiments, R₁ may be a substituted or unsubstituted C₁₋₈alkyl, a substituted or unsubstituted C₂₋₈ alkenyl, or a substituted orunsubstituted C₂₋₈ alkynyl, wherein the substituted C₁₋₈ alkyl, thesubstituted C₂₋₈ alkenyl, and the substituted C₂₋₈ alkynyl may besubstituted with hydroxyl or C₁₋₅ alkyl.

The effective amount added to the medium in an industrial process can bereadily determined by one of ordinary skill in the art. An effectiveamount would depend at least partially on the medium's hydrogen sulfidecontent. Generally, if a medium contains high levels of hydrogen sulfidethen more of the composition may be required. In some embodiments, theeffective amount may be in a range from about 0.00001 ppm to about100,000 ppm.

The industrial process may utilize or process crude oil, diesel fuel,asphalt or the like. The composition may be added to a medium in theindustrial process, such as crude oil, diesel fuel, asphalt, orcombinations thereof in order to remove unwanted hydrogen sulfide.

The composition may be added to the process continuously or dosedintermittently. A programmed logic controller may control the additionof the composition to the process. The method may include sensors thatdetect levels of hydrogen sulfide. The sensors may be in communicationwith the PLC. Once levels of hydrogen sulfide approach or reach apredetermined threshold the composition may be added to process.

The compositions and methods disclosed herein may be especially usefulfor removing hydrogen sulfide from hot asphalt where the use of aqueousor volatile solvents presents safety or toxicity concerns.

EXAMPLES Example 1 Dissolution of Hexamine in Cinnamyl Alcohol andGlycerin

Slurries were prepared by mixing hexamine in cinnamyl alcohol or amixture of cinnamyl alcohol and glycerin at about room temperature. Thecompositions were then allowed to sit undisturbed for two days and theclear supernatant decanted off and analyzed for composition. As theresults below illustrate, clear stable solutions of hexamine in variousratios of glycerin and cinnamyl alcohol were obtained.

TABLE 1 Composition of Stable Solutions by Weight % Hexamine CinnamylAlcohol Glycerin (<1% water) 7 93 0 10 84 6 11 78 11 10 68 22 7 59 34 750 43 8 37 55 5 32 63 8 16 76

All of the compositions and methods disclosed and claimed herein can bemade and executed without undue experimentation in light of the presentdisclosure. While this invention may be embodied in many differentforms, there are described in detail herein specific preferredembodiments of the invention. The present disclosure is anexemplification of the principles of the invention and is not intendedto limit the invention to the particular embodiments illustrated. Inaddition, unless expressly stated to the contrary, use of the term “a”is intended to include “at least one” or “one or more.” For example, “acompound” is intended to include “at least one compound” or “one or morecompounds.”

Any composition disclosed herein may comprise, consist of, or consistessentially of any of the compounds/components disclosed herein. Inaccordance with the present disclosure, the phrases “consist essentiallyof,” “consists essentially of,” “consisting essentially of,” and thelike, limit the scope of a claim to the specified materials or steps andthose materials or steps that do not materially affect the basic andnovel characteristic(s) of the claimed invention.

Any ranges given either in absolute terms or in approximate terms areintended to encompass both, and any definitions used herein are intendedto be clarifying and not limiting. Notwithstanding that the numericalranges and parameters setting forth the broad scope of the invention areapproximations, the numerical values set forth in the specific examplesare reported as precisely as possible. Any numerical value, however,inherently contains certain errors necessarily resulting from thestandard deviation found in their respective testing measurements.Moreover, all ranges disclosed herein are to be understood to encompassany and all subranges (including all fractional and whole values)subsumed therein.

Furthermore, the invention encompasses any and all possible combinationsof some or all of the various embodiments described herein. It shouldalso be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the invention and withoutdiminishing its intended advantages. It is therefore intended that suchchanges and modifications be covered by the appended claims.

What is claimed is:
 1. A composition, comprising: a monolignol alcoholand a compound of formula (I) or formula (II)

where R₁ is a substituted or unsubstituted C₁₋₈ alkyl, a substituted orunsubstituted C₂₋₈ alkenyl, or a substituted or unsubstituted C₂₋₈alkynyl, wherein the substituted C₁₋₈ alkyl, the substituted C₂₋₈alkenyl, and the substituted C₂₋₈ alkynyl are substituted with hydroxylor C₁₋₅ alkyl.
 2. The composition of claim 1, wherein the monolignolalcohol is selected from the group consisting of p-coumaryl alcohol,coniferyl alcohol, sinapyl alcohol, cinnamyl alcohol, and anycombination thereof.
 3. The composition of claim 1, wherein themonolignol alcohol is cinnamyl alcohol.
 4. The composition of claim 1,wherein the monolignol alcohol is coniferyl alcohol.
 5. The compositionof claim 1, wherein the compound is hexamine.
 6. The composition ofclaim 1, further comprising a C₂₋₈ polyol.
 7. The composition of claim6, wherein the C₂₋₈ polyol is glycerin.
 8. The composition of claim 1,comprising the compound of formula (I), cinnamyl alcohol, and glycerin.9. The composition of claim 1, wherein the composition comprises about 2to about 20 weight percent of the compound of formula (I) or formula(II).
 10. The composition of claim 1, wherein the composition comprisesabout 10 to about 98 weight percent of the monolignol alcohol.
 11. Thecomposition of claim 6, wherein the composition comprises about 2 toabout 80 weight percent of the C₂₋₈ polyol.
 12. The composition of claim6, wherein a weight ratio of the monolignol alcohol to the C₂₋₈ polyolis about 10:1 to about 20:1.
 13. The composition of claim 1, wherein aweight ratio of the compound of formula (I) or formula (II) tomonolignol alcohol is about 1:15 to about 1:1.
 14. The composition ofclaim 1, wherein the composition comprises an amount of water that isless than about 1% by weight.
 15. The composition of claim 1, whereinthe composition excludes water.
 16. The composition of claim 1, whereinthe composition comprises a pH greater than about
 7. 17. A method forscavenging hydrogen sulfide in an industrial process, comprising: addingan effective amount of a composition to a medium in the industrialprocess, wherein the composition comprises a monolignol alcohol and acompound of formula (I) or formula (II)

where R₁ is a substituted or unsubstituted C₁₋₈ alkyl, a substituted orunsubstituted C₂₋₈ alkenyl, or a substituted or unsubstituted C₂₋₈alkynyl, wherein the substituted C₁₋₈ alkyl, the substituted C₂₋₈alkenyl, and the substituted C₂₋₈ alkynyl are substituted with hydroxylor C₁₋₅ alkyl.
 18. The method of claim 17, further comprising a C₂₋₈polyol, and wherein the monolignol alcohol is cinnamyl alcohol.
 19. Themethod of claim 17, wherein the effective amount is in a range fromabout 0.00001 ppm to about 100,000 ppm.
 20. The method of claim 17,wherein the medium is selected from the group consisting of crude oil,diesel fuel, asphalt and any combination thereof.